Form PA-40 Schedule G-L is used to claim a credit for taxes paid to another state.
You can get back into the input by going into the state tax interview section.
1. Select Continue to the right of PA
2. Proceed through the screens until you see the tax summary similar to the sample shown below:
3. Select Taxes and Credits.
4. Continue through the screens until you see Taxes Paid to Other States Summary
You will be able to edit your information in this section.